Unit #6

Question 1

What is the function of a muscle fiber?

Answer 1

Generating movement through contraction.

Question 2

What is the structure of a muscle fiber?

Answer 2

Muscle fibers are individual muscle cells with specific proteins and structures to enable shortening or contracting of each cell. Each muscle fiber is connected to the peripheral nervous system by one of several neuromuscular junctions to a motor neuron. This allows for a signal to relay to multiple muscle fibers simultaneously.

Question 3

What organelles are inside of a muscle fiber?

Answer 3

Inside of a muscle fiber is the organelle called a myofibril (a cylindrical structure) arranged in parallel bundles. They are made of sarcomeres.

Question 4

What is a sarcomere?

Answer 4

A sarcomere is a repeated contractile unit found in skeletal and cardiac muscle tissue
Each sarcomere contains proteins called myosin (thick filaments) and actin (thin filaments).

Question 5

What is the cytoplasm of a muscle fiber?

Answer 5

Sacroplasma

Question 6

What is the name of a plasma membrane of a muscle fiber?

Answer 6

Sarcolemma

Question 7

What is the function of the sarcoplasmic reticulum?

Answer 7

The sarcoplasmic reticulum is the endoplasmic reticulum of a muscle fiber. The sarcoplasmic reticulum stores and releases additional calcium ions for contraction.

Question 8

What is a T-tuble?

Answer 8

A T-tubule is an extension of the sarcolemma that allows electrical impulses to reach the inner myofibrils.

Question 9

What are Connective Tissue Sheaths?

Answer 9

Connective tissue sheaths are protective, fibrous layers that surround, support, and separate muscles, nerves, and organs. In skeletal muscle, they are organized into three layers—endomysium, perimysium, and epimysium.

Question 10

What is the sliding filament action of muscle contraction?

Answer 10

The sliding filament action of muscle contraction is when actin and myosin slide against each other. Myosin grabs onto actin and pulls it along. Myosin utilizes ATP and calcium ions to bend and bind to other actin strands.

Question 11

Why is Ca++ important to muscle contraction?

Answer 11

Ca++ is important to muscle contraction because the calcium ions from the sarcoplasmic reticulum bind to troponin in the tropomyosin complex that are shielding the active sites on the actin filament. This causes the active sites to be exposed allowing for myosin filament to bind.

Question 12

What is an antagonist leg muscle?

Answer 12

An antagonistic muscle is a muscle pair that moves the joint in opposite directions. When one contracts the other relaxes.

Question 13

What is an example of an antagonist leg muscle?

Answer 13

An example of an antagonist leg muscle would be the quadriceps that act as extensors that straighten the knee and the hamstrings that act as flexors and bend the knee.

Question 14

How do muscles and bones interact to cause movement?

Answer 14

Muscles are made up of small fibers that are connected to bones. Bones have structure for muscles to hold on to and in turn the muscles moving make the bones move.

Question 15

What is a tendon?

Answer 15

A tendon is a tough, fibrous band of connective tissue, composed primarily of collagen, that attaches muscle to bone.

Question 16

What is a joint?

Answer 16

A joint is the location in the body where two or more bones connect, enabling structural support and movement.

Question 17

What is the difference between fast twitch and slow twitch muscles when it comes to color?

Answer 17

Fast twitch muscles are white while slow twitch muscles are red. This is because of the myoglobin content (a pigment that stores oxygen) and capillary density.

Question 18

What are slow twitch muscles for?

Answer 18

Slow twitch muscles are for long and continuous activity such as walking and posture.

Question 19

What are fast twitch muscles for?

Answer 19

Fast twitch muscles are for fast and powerful activity such as sprinting and weightlifting.

Question 20

What type of muscle carries out aerobic respiration?

Answer 20

Slow twitch (which requires mores mitochondria). They rely on aerobic respiration because their ATP need is continuous and low.

Question 21

What type of muscle carries out anaerobic glycolysis?

Answer 21

Fast twitch (which requires less mitochondria). They rely on glycolysis because of how quick and abundant their ATP needs are.

Question 22

What are proprioreceptors?

Answer 22

Proprioreceptors are sensory receptors in the body that detect things like posture and movement of muscles and joints.

Question 23

What are different types of proprioceptors?

Answer 23

Muscle spindles (detect how long a muscle is), Golgi tendon organs (tension), and joint receptors (joint angle/position).

Question 24

What are the three types of muscles in the body?

Answer 24

Smooth muscle, cardiac muscle, and skeletal muscle.

Question 25

What is smooth muscle?

Answer 25

Smooth muscles are found in the blood vessels, the lungs, bladder, reproductive systems, and gastrointestinal tract. They are involuntary and regulated by autonomic motor neurons in the sympathetic and parasympathetic nervous systems. They are uninucleated.

Question 27

Do smooth muscles contain myofibrils?

Answer 27

Smooth muscle does not contain myofibrils or sarcomeres, which is why it lacks the striations (stripes) found in skeletal and cardiac muscle. Instead of organized bundles of myofibrils, smooth muscle cells possess a less ordered network of actin and myosin filaments that anchor to dense bodies throughout the cytoplasm.

Question 28

What is cardiac muscle?

Answer 28

Cardiac muscles make up the body of the heart and are also involuntary. They have a unique, branched structure, and they are multinucleate and striated. Contraction of the heart is produced by spontaneous depolarization, with the parasympathetic nervous system releasing ACh into the heart to slow the rate of polarization during rest.

Question 29

What happens when cardiac muscle is stimulated by exercise or stress?

Answer 29

When stimulated by exercise or stress, the sympathetic nervous system releases norepinephrine and epinephrine to increase the rate and force of contractions to elevate blood flow.

Question 30

What is skeletal muscle?

Answer 30

Skeletal muscles are made of long, multinucleate, striated fibers that anchor to the skeleton. Contraction of these muscles exert a pulling force on the bones of the skeleton, facilitating movement.

Question 31

Does cardiac or smooth muscle require the nervous system to move?

Answer 31

No actually (unlike skeletal muscle), cardiac muscle creates its own rhythm and is myogenic and has its one pacemaker cells but the nervous system can speed it up, and smooth muscle can respond to things like stretching, hormones, or chemical changes but the nervous system still can adjust how active it is. They both still rely more heavily on the nervous system.

Question 32

Why are muscles important in maintaining homeostasis?

Answer 32

They are important in maintaining homeostasis because they assist in thermal regulation, the digestion system/ waste removal. Muscles produce heat as a byproduct of muscle contraction. Muscles also work to remove waste and ensure nutrients continue to be absorbed.